Evolutionary Conservation and Divergence of Genes Encoding 3-Hydroxy-3-methylglutaryl Coenzyme A Synthase in the Allotetraploid Cotton Species .

Polyploidization is important for the speciation and subsequent evolution of many plant species. Analyses of the duplicated genes produced via polyploidization events may clarify the origin and evolution of gene families. During terpene biosynthesis, 3-hydroxy-3-methylglutaryl coenzyme A synthase (HMGS) functions as a key enzyme in the mevalonate pathway. In this study, we first identified a total of 53 genes in 23 land plant species, while no genes were detected in three green algae species. The phylogenetic analysis suggested that plant genes may have originated from a common ancestral gene before clustering in different branches during the divergence of plant lineages. Then, we detected six genes in the allotetraploid cotton species (), which was twice that of the two diploid cotton species ( and ). The comparison of gene structures and phylogenetic analysis of genes revealed conserved evolution during polyploidization in . Moreover, the expression patterns indicated that six genes were expressed in all tested tissues, with most genes considerably expressed in the roots, and they were responsive to various phytohormone treatments and abiotic stresses. The sequence and expression divergence of duplicated genes in implied the sub-functionalization of and as well as and , whereas it implied the pseudogenization of and . Collectively, our study unraveled the evolutionary history of genes in green plants and from diploid to allotetraploid in cotton and illustrated the different evolutionary fates of duplicated genes resulting from polyploidization.